Serena Williams continues to impress. 

The tennis champion won the Australian Open Tennis Championships 2017 in January,  her seventh title down under and 23rd Grand Slam singles title overall.

Now, thanks to a Snapchat she posted — and then quickly deleted — on Wednesday, fans are speculating she did it all while pregnant. 

Serena Williams/Snapchat - nytimes.com

The snap is captioned with the words "20 weeks," leading followers to speculate that she was 20 weeks pregnant. If so, that would mean she would have been pregnant while competing in — and winning — the Australian Open.

Twitter users freaked out with praise.

How safe is it to participate in physical activity while pregnant? We asked a doctor to find out. 

"Exercise is very safe, even in early pregnancy," Dr. Kristin Bendikson of the University of Southern California Fertility Clinic told ATTN: via email. "There is strong evidence that exercise in pregnancy does not increase the chance of miscarriage or early delivery. In fact, exercising can actually have beneficial affect on a woman's pregnancy and labor."

For those who of us who aren't Serena Williams, Dr. Bendikson does note "pregnancy is probably not the time to start aggressively training." But "for an elite athlete, it would most likely be wise to train to maintain their current fitness level, not train to build and improve it."

Williams hasn't made an official statement, and of course, winning the Australian Open is an impressive feat all on its own. If she won it while pregnant, that's yet another example of how Williams has continued to defy expectations set for her.